A study of the properties of transcription of an oncogenic animal virus is proposed as an approach to the elucidation of the control of expression of viral genes with oncogenic potential and of mammalian genes in general. We have selected the herpes simplex viruses for several reasons: they have a DNA genome and a mammalian host, many new experimental opportunities are open for the study of their transcription, and, very importantly, these viruses are involved in diseases of man and have a probable relationship to oncogenesis. Our plan is to develop an in vitro transcription system in which RNA molecules synthesized from herpes DNA are similar to those produced during infection. This system will be used to examine various aspects of the control of transcription, the amount of RNA produced, and some of the characteristics of the RNA molecules. Initial studies have concentrated on purification of RNA polymerase species appropriate for use in the in vitro transcription system. Further work will involve a search for factors affecting the specificity of transcription and a determination of the effect of the physical state of the herpes DNA on its transcription. Virus RNA molecules synthesized in vitro will be characterized by size and capacity to self-anneal. By hybridization experiments, we will determine whether these RNA's are homolgous to RNA's synthesized at particular times during virus maturation in vivo. Hybridization experiments will also show us whether these RNA's are transcribed from particular template fragments produced by digestion with bacterial restriction enzymes. These data should provide information concerning the genetic organization of the herpes simplex genome. Later studies will include more general aspects of virus transcription such as binding of polymerase, initiation, and termination. Herpes simplex virus type 1 (HSV-1) will be used in initial experiments with KB and HEp-2 established human cell lines serving as model host cells. Later experiments will involve comparative studies with HSV-2, transformed hamster embryo fibroblasts, and tumors derrived from herpes-transformed cells.